Zig-zag sewing machine with simplified material feed control gearing



Aug. 12, 1958 w, ENGEL 2,846,966

ZIG-ZAG SEWING MACHINE WITH SIMPLIFIED MATERIAL FEED CONTROL GEARING Filed Jan. 18, 1956 4 Sheets-Sheet 1 Aug. 12, 1958 2,846,966

W. ENGEL ZIG-ZAG SE NG H WITH SIMPL ED HATER F C ROL GEARIN Filed Jan. 18, 1956 4 Sheets-Sheet 2 Aug. 12, 1958 w. ENGEL 2,846,966

ZIG-ZAG SEWING MACHINE WITH SIMPLIFIED MATERIAL FEED CONTROL GEARING Filed Jan. 18, 1956 4 Sheets-Sheet 3 Aug. 12, 1958 f w. ENGEL ,9

ZIG-ZAG SEWING MACHINE WITH SIMPLIFIED MATERIAL FEED CONTROL GEARING Filed Jan. 18 1956 -4 Sheets-Sheet 4 rates The invention relates to a zig-zag sewing machine, particularly to the material advancing or feeding and gripping mechanisms of such a machine.

In accordance with the invention a zig-zag sewing machine is provided which makes it possible to obtain clean stitch formation even when operating rapidly with a large number of stitches per time unit. For this purpose a known type of sewing machine is utilized where the material feeding is effected by a pulling movement of the toothed head or dog, i. e. where the advancing or feed shaft is located behind the needle bar in relation to the machine operator.

If it is desired with such a type of zig-zag sewing machine to obtain a higher number of stitches combined with a clean stitch formation it is necessary that the prerequisites for vibrationless and tangle-proof operation of the power transmission means on which the material advancing or feeding depends be fulfilled.

With this object in view and with reference to the foregoing explanations the invention provides that the driving of the feeder shaft is initiated from the hook or gripper drive shaft, which is also located behind the needle bar, by means of an eccentric member or cam with a toggle lever mechanism interposed. Accordingly the driving force is supplied by way of a cam disposed upon the hook or gripper drive shaft and by means of an essentially vertically extending connecting rod as well as a substantially horizontally disposed toggle lever mechanism.

By means of this feature of the invention for the Zig-zag sewing machine which is being considered here, the separate driving connections for the gripper drive shaft on the one hand and for the material advancing shaft on the other hand, to the shaft disposed in the arm of the sewing machine, which were necessary heretofo-re, are obviated. Thus, the separate power transmission means from the arm shaft to the advancing shaft are saved, with the consequence that the respective oscillating masses in the machine are eliminated.

Moreover, the solution of the problem in accordance with the invention as described comprises the feature that the cam for the advancing movement of the material being sewed is closely approached to the transversely disposed hook or gripper shaft together with the associated toggle lever mechanism. This means that the advancing Unite shaft which is driven by the gripper drive shaft can be made short so that no danger of tangling is introduced. The close approach of the cam for the advancing of the sewing material together with the associated toggle mechanism towards the transverse gripper shaft, provides also the advantageous effect that the entire power transmission means are concentrated below the base plate of the sewing machine in a narrow space, substantially in the area of the sewing machine head, so that, in addition, space is made below the base plate to accommodate the machine motor, a transformer or the like, in a manner to save space.

Extensive tests have shown that these features of the invention insure reliable and safe operation of a zig-zag sewing machine with a stitch count of at least 5,000 revolutions per minute. This result has become possible for the first time with zig-zag sewing machines having a transversely disposed gripper or hook. This type of gripper arrangement is known to be particularly advantageous atom for zig-zag sewing machines which are to be utilized for an extensive range of applications.

It was by no means near at hand to achieve this objective of the invention with zig-zag sewing machines having the gripper disposed transversely with respect to the material advancing device, by using the aforementioned means for the solution. The disposition of the connecting rod which extends substantially vertically requires that a certain minimum length of the connecting rod may not be exceeded for structural reasons and it could not be anticipated from the beginning that it is possible with such a relatively short connecting rod length in association with substantially horizontally extending toggle levers which must likewise be of relatively short length, to obtain a drive for rapidly turning machines .which avoids unnecessarily high power in the transmission members and thus permits quiet running of the machine without pounding.

Further features and details of the invention are shown in the embodiment illustrated in the drawing in which:

Fig. 1 is a plan view upon'the underside of the base plate of the sewing machine,

Fig. 2 is a side view of the toggle lever arrangement of the advancing mechanism with the setting of the setting crank for zero stitch length taken along line l111 in Fig. l and looking in the direction indicated by the arrows,

Fig. 3 is a side view of the lifting mechanism from the left in the direction of arrow III in Fig. 1,

Fig. 4 is a side view of the toggle lever arrangement from the right with the setting of the crank for maximum forward carrying movement as seen in arrow direction IV in Fig. 1,

Fig. 5 is a side view of the toggle lever arrangement from the right with the crank set for maximum backward carrying movement as seen in arrow direction IV in accordance with Fig. l and Fig. 6 is a perspective view of the toggle lever arrangement.

The gripper or hook drive shaft 1 is journalled at several locations in the base plate 2 which is indicated in dot and dash lines. It is driven by the main shaft of the machine (not illustrated) by way of a belt which engages the teeth on the pulley 1 fastened to the gripper drive shaft 1. The gripper drive shaft carries at its forward end a worm gear 34 which has engagement with the worm gear 35 secured to the gripper shaft 36. The gripper shaft 36 extends transversely of the gripper drive shaft 1 and supports the gripper or hook 33 the plane of rotation of which is disposed transversely of the material advancing direction. The vertical movement (lift) as well as the horizontal movement (push) of the toothed head member or dog 10 are derived from the gripper drive shaft by means of cams 3 and 21 which are mounted in the proximity of the hook shaft'36. The push cam 21 is encompassed by the bore 22a of the substantially vertically disposed connecting rod 22. The connecting rod 22 has a bifurcated end which engages the eye 23a of the toggle joint member 23 by way of rod 24. Rods 24 and 32 are disposed between the toggle joint members 29 and 30. Also the lever 31 and the crank 25 enclose the rod 32 between them. The lever 31 is journalled on the shaft 31bwhich is secured to the base plate 2, while the adjusting crank 25 is rigidly mounted upon the adjusting shaft 28 which is journalled cQIlIlfiQtfid at theother end to the advancing shaft 14 by way of crank 14a and stud 14b. The advancing shaft 14 is journalled between pintles 15, 16 which are securely fastened to lugs 17 and 18. It is provided with two lever arms 12 and 13 in the bores of which the advancing or feeder bar 10 is journalled by means of stud 11. The feeder bar 10 supports the toothed head member dog 10'. The lift motion for the dog 10 is derived from cam 3 which is secured to the gripper drive shaft 1. The connecting rod 4 engages the cam 3 with a bore 4a while engaging by means of another bore 4b the stud 7 which is secured to the angle lever 5. The angle lever 5 is journalled on a bolt 7 secured to the base plate 2 and carries on its substantially horizontally extending lever arm a stud 8 on which the roller 9' is journalled which is engaged on both sides by the cheeks of the feeder arm 10.

When the handle of the stitch setting lever 26a is moved to the upward position the crank 25 is moved to the downward position (Fig. 5) by way of the pull rod 26, lever 27 and the shaft 28. In this position of the rod 32 which serves as the support for the toggle joint 29, 30 and 25, the shaft 24 is rocked about shaft 32 along an are having the radius of levers 29, and 30, as the cam 21 is rotated. As a result the crank 140, the feeder shaft 14, the feeder bar 10, the toothed head 10 are moved to the left by way of toggle member 23, i. e. in the direction of the operator. In the position of the toggle levers illustrated in Fig. 5 the dog If? is in its uppermost position. The material is moved toward the operator.

The material is moved away from the operator when the handle of the stitch setting lever 26a is in the lowermost position and thus the adjusting crank is in the uppermost pivotal position (Fig. 4). In the illustrated position of the toggle lever arrangement the cam 21 is in the lower position. Turning the cam 21 causes the dog 10 to be moved in the direction away from the operator while in the uppermost position, i. e. above the stitch plate.

In Fig. 2 the adjusting crank 25 is in the central position. In this position of the toggle arrangement the joints 29 30 and 23 are equally flexed upwardly and downwardly out of the position of alignment, whereby the stud 14b is practically'in position of rest and thus the dog 10 moves essentially in vertical direction only, thus not transporting any material.

It is clear from Fig. 1, that there is suflicient space below the base plate 2 to accommodate a motor 38 and other components such as transformer 37, or the like.

Having now described my invention with reference to the embodiment illustrated in the drawings, I do not wish to be limited thereto but what I desire to protect by Letters Patent of the United States is set forth in the appended claims.

I claim:

1. In a zig-zag sewing machine of the type having a needle bar, a machine base having a cloth plate and front and rear longitudinal sides, a hook rotatable in a plane disposed perpendicularly to the direction of material feed, a hook supporting shaft, and a hook drive shaft having driving engagement at one end with said hook supporting shaft and extending rearwardly of said hook longitudinally of said machine along said rear side and having a driven member at the other end, a feed dog supported by a feed bar. above said book, a material feed shaft extending rearwardly of said hook presenting lever means supporting said feed bar, a stitch setting mechanism having a member extending externally of the machine, a cam on said hook drive shaft, a connecting rod having one end in operative engagement with said cam and the other end in engagement with a link member of said stitch setting mechanism, a crank arm on said feed shaft and a substantially horizontally extending toggle j i ha ing a jo por on in ngage n wi ai connecting rod, one arm in engagement with said crank arm and another arm defining said link member of said stitch setting mechanism, said cam, said connecting rod, said crank arm, said feed shaft, said feed bar and said toggle joint being concentrated in an area extending proximate said hook and said dogand on one side thereof over a length substantially that of said feed bar, thereby reducing the dimensions of said feed shaft and reducing vibration of the machine mechanism.

2. In a zig-zag sewing machine of the type having a needle bar, a machine base having a cloth plate and front and rear longitudinal sides, a hook rotatable in a plane disopsed perpendicularly to the direction of material feed, a hook supporting shaft, and a hook drive shaft having driving engagement at one end with said hook supporting shaft and extending rearwardly of said hook longitudinally of said machine along said rear side and having a driven member at the other end, a feed dog supported by a feed bar above said hook, a material feed shaft extending rearwardly of said hook presenting lever means supporting said feed bar, a stitch setting mechanism having a member extending externally of the machine, a cam on said hook drive shaft, a connecting rod having one end in operative engagement with said cam and the other end in engagement with a link member of said stitch setting mechanism, a crank arm on said feed shaft and a substantially horizontally extending toggle joint having a joint portion in engagement with said connecting rod, one arm in engagement with said crank arm and another arm defining said link member of said stitch setting mechanism, said cam, said connecting rod, said crank arm, said feed shaft, said feed bar and said toggle joint being concentrated in an area extending proximate said hook and said dog and on one side thereof over a length substantially that of said feed bar, and said crank arm on said feed shaft being spaced from said lever means supporting said feed bar by a distancenot exceeding the axial length of said lever means, thereby reducing the dimensions of said feed shaft and reducing vibration of the machine mechanism.

3. In a zig-zag sewing machine of the type having a needle bar, a machine base having a cloth plate and front and rear longitudinal sides, a hook rotatable in a plane disposed perpendicularly to the direction of material feed, a hook supporting shaft, and a hook drive shaft having driving engagement at one end with said hook supporting shaft and extending rearwardly of said hook longitudinally of said machine along said rear side and having a driven member at the other end, a feed dog supported by a feed bar above said hook, a material feed shaft extending rearwardly of said hook presenting lever means supporting said feed bar, a stitch setting mechanism having a member extending externally of the machine, a cam on said hook drive shaft, a connecting rod having one end in operative engagement with said cam and the other end in engagement with a link member of said stitch setting mechanism, a crank arm on said feed shaft and a substantially horizontally extending toggle joint having a joint portion in engagement with said connecting rod, one arm in engagement with said crank arm and another arm defining said link member of said stitch setting mechanism, said cam, said connecting rod, said crank arm, said feed shaft, said feed bar and said toggle joint being concentrated in an area extending proximate to said hook and said dog and on one side thereof over a length substantially that of said feed bar and said toggle joint extending substantially parallel to said feed bar and said hook supporting shaft, thereby reducing the dimensions of said feed shaft and reducing vibration of the machine mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 2,672,112 Hale Mar. 16, 1954 2,681,627 Meloy June 22, 1954 

